<!DOCTYPE html>
<html>
<head>
<style>
body {
  counter-reset: section;
}

h2::before {
  counter-increment: section;
  content: "Section " counter(section) ": ";
}
</style>
</head>
<body>

<h1>使用 CSS 计数器：</h1>
<h2>HTML 教程</h2>
<h2>CSS 教程</h2>
<h2>JavaScript 教程</h2>

</body>
</html>
